This will be a phase Ia, unblinded, dose-escalation trial examining the toxicity and tolerability of the antioxidant idebenone in patients with FRDA. Our primary objective is to determine the maximum tolerated single dose of idebenone in patients with FRDA. Our secondary objective is to document the pharmacokinetics of single-dose idebenone in this population. We aim to enroll 48 patients divided evenly among three age cohorts: children (ages 5-11), adolescents (ages 12-17), and adults (age greater than or equal to 18). Each age cohort will be studied independently. Three patients from each cohort will receive one day of oral idebenone followed by inpatient monitoring for 72 hours. If dose-limiting toxicity (DLT) is not observed during the 72-hour study period, three new patients will receive the next highest dose. If one of three patients experiences DLT, three new patients will receive the same dose. Within each cohort, the dose will be escalated until the maximum tolerated dose (MTD) is established. The MTD will be defined as one dose below that which resulted in DLT in any two patients within a cohort.